Hi,
As far as I understand the discussion, you do not use the SAP standard assesment? You created a custom phap template? Is That right?
In case of a standard template please make sure that IT7408/09 is filled correctly with the correct status(!!!).
Did you configure OADP for the Manager's Talent Information. ( That is the step before the standard Talent Assessment starts... the list with employees assigned to the manager?) These employees will appear in the Talent Grid (and only theses) If that list is not working correct the talent grid is not filled with talent data.
I would suggest to use the standard assessment to check whether it is working. Later you can cerate a custom one.
best regards
Martin Hastik